The present invention generally relates to stent deployment systems and more particularly pertains to deployment systems that facilitate the exchange and precise positioning of various implements at the deployment site with minimal effort and without the risk of injury to the vasculature.
Vascular therapy is often a multi-step process involving treatment with a variety of devices. Initially, angiography is performed in order to map the lesion and arterial geometry. A guiding catheter is subsequently placed into the ostium of the artery after which a small diameter guide wire is extended through the diseased legion. A low profile balloon is then advanced along the guide wire into position within the target site and inflated to pre-dilate the site. After the inner diameter of the lesioned area has been sufficiently increased, a stent deployment system is maneuvered into place. Such system may consist of a catheter carrying a self-expanding stent that is maintained in its collapsed configuration by a restraining sheath. Upon retraction of the sheath, the stent automatically expands and the deployment system in withdrawn. Subsequent thereto, a large high pressure balloon catheter is advanced through the vasculature and positioned within the expanded stent. Inflation of the balloon serves to post-dilate the stented area. Withdrawal of the balloon catheter and introduction of an ultrasound imaging catheter (IVUS) allows the success of the procedure to be assessed. The post dilation and imaging steps may have to be repeated until a satisfactory result is obtained.
A number of disadvantages are inherent in the above-described procedure. The repeated introduction, precise positioning, and withdrawal of the various devices is not only time consuming but, each time a device is shifted within the artery, the risk of dislodging embolic plaque and causing a stroke thereby is enhanced. Additionally, the failure to precisely position each newly introduced device may cause problems. For instance, an imprecisely placed high pressure balloon may not only cause the stent to become distorted, but expansion against unstented, unprotected tissue could cause injury. A poorly placed imaging catheter would not only yield poor imagery but would require further repositioning.
A stent deployment system is needed that simplifies the stent deployment procedure, expedites the operation and reduces the risk of injury to the artery as well as the risk of dislodging embolic plaque.